A number of techniques are known in the art for rendering flame retardant addition curing silicone rubber compositions which cure into elastomers. The most basic technique is the addition of platinum compounds to organopolysiloxanes. The addition of benzotriazole, hydrazine or the like is also known effective for improving flame retardance. Fumed titanium oxide, cerium oxide, cerium hydroxide, iron oxide and carbon powder are also ascertained to be effective. All the silicone rubber compositions to which these compounds are added are also filled with reinforcing inorganic fillers such as fumed silica and ground quartz.
Among transparent materials based on organopolysiloxane, it is known to use silicone gel as a filler in members associated with optical equipment, as a protective material for hybrid integrated circuits used in electric and electronic parts for automobiles, and as a protective sealant for commercial power modules. Flame retardance is required in these applications as well. Flame retardance is developed by the addition of amine compounds as disclosed in Japanese Patent No. 2,864,944 corresponding to U.S. Pat. No. 5,516,838 or by the addition of phosphorus compounds as disclosed in JP-A 8-231858.
For more efficient working on the user side and from the characteristics of IC chips to be protected, silicone compositions are recently required to be curable at lower temperatures than in the prior art and ven at room temperature, and be formulated as one package. However, compositions using amine compounds as disclosed in Japanese Patent No. 2,864,944 are very difficult to cure at low temperatures and even at room temperature while maintaining flame retardance.